U.S. patent application number 13/149841 was filed with the patent office on 2012-12-06 for overlay mark set and method for positioning two different layout patterns.
Invention is credited to Chui-Fu Chiu, Chun-Yen Huang.
Application Number | 20120308788 13/149841 |
Document ID | / |
Family ID | 47234200 |
Filed Date | 2012-12-06 |
United States Patent
Application |
20120308788 |
Kind Code |
A1 |
Chiu; Chui-Fu ; et
al. |
December 6, 2012 |
OVERLAY MARK SET AND METHOD FOR POSITIONING TWO DIFFERENT LAYOUT
PATTERNS
Abstract
An overlay mark set includes a substrate, a first overlay mark
and a second overlay mark. The first overlay mark is disposed on
the substrate for representing a first layout pattern. The second
overlay mark is also disposed on the substrate for representing a
second layout pattern. In particular, the first overlay mark is in
direct contact with the second overlay mark.
Inventors: |
Chiu; Chui-Fu; (Taoyuan
City, TW) ; Huang; Chun-Yen; (Taoyuan City,
TW) |
Family ID: |
47234200 |
Appl. No.: |
13/149841 |
Filed: |
May 31, 2011 |
Current U.S.
Class: |
428/201 ;
156/235; 156/64; 430/325 |
Current CPC
Class: |
Y10T 428/24851 20150115;
G03F 7/70633 20130101; G03F 7/70683 20130101 |
Class at
Publication: |
428/201 ;
430/325; 156/235; 156/64 |
International
Class: |
G03F 7/20 20060101
G03F007/20; B44C 1/17 20060101 B44C001/17; B32B 37/02 20060101
B32B037/02; B32B 3/10 20060101 B32B003/10 |
Claims
1. An overlay mark set, comprising: a substrate; a first overlay
mark representing a first layout pattern and disposed on said
substrate; and a second overlay mark representing a second layout
pattern and disposed on said substrate, wherein said first overlay
mark is in direct contact with said second overlay mark.
2. The overlay mark set of claim 1, further comprising: said first
layout pattern disposed on said substrate; and said second layout
pattern disposed on said substrate.
3. The overlay mark set of claim 2, wherein said first layout
pattern and said second layout pattern are disposed in an alternate
order.
4. The overlay mark set of claim 1, wherein said first overlay mark
represents a previous layout pattern.
5. The overlay mark set of claim 4, wherein said second overlay
mark represents a current layout pattern.
6. The overlay mark set of claim 1, wherein said second overlay
mark is higher than said first overlay mark.
7. The overlay mark set of claim 1, wherein said first overlay mark
is a polygon.
8. The overlay mark set of claim 1, wherein said first overlay mark
is oval.
9. The overlay mark set of claim 1, wherein said second overlay
mark is a polygon.
10. The overlay mark set of claim 1, wherein said second overlay
mark is oval.
11. A method for positioning two layout patterns, comprising:
providing a substrate; forming a first layout pattern and a first
overlay mark on said substrate; processing said first overlay mark;
forming a second layout pattern and a second overlay mark on said
substrate, wherein said second overlay mark is indirect contact
with said first overlay mark; and positioning said second layout
pattern.
12. The method for positioning two layout patterns of claim 11,
wherein forming said first layout pattern and said first overlay
mark on said substrate comprises: forming a first material layer on
said substrate; and transferring said first layout pattern into
said first material layer by exposure and development.
13. The method for positioning two layout patterns of claim 11,
wherein processing said first overlay mark comprises: hard-baking
said first overlay mark.
14. The method for positioning two layout patterns of claim 11,
wherein forming said second layout pattern and said second overlay
mark on said substrate comprises: forming a second material layer
on said substrate, wherein said second material layer covers said
first layout pattern; and transferring said second layout pattern
into said second material layer by exposure and development.
15. The method for positioning two layout patterns of claim 11,
wherein said first layout pattern and said second layout pattern
are disposed in an alternate order.
16. The method for positioning two layout patterns of claim 11,
further comprising: positioning said first overlay mark.
17. The method for positioning two layout patterns of claim 16,
wherein positioning said first overlay mark comprises: recording
the position of said first overlay mark digitally.
18. The method for positioning two layout patterns of claim 16,
wherein positioning said first overlay mark comprises: taking an
image of said first overlay mark.
19. The method for positioning two layout patterns of claim 16,
wherein positioning said second overlay mark comprises: recording
the position of said second overlay mark and said first overlay
mark together digitally; and comparing the position of said second
overlay mark and said first overlay mark with the position of said
first overlay mark alone.
20. The method for positioning two layout patterns of claim 18,
wherein positioning said second overlay mark comprises: taking an
image of said first overlay mark and said second layout pattern
together; and comparing said image of said first overlay mark and
said second overlay mark with said image of said first overlay mark
alone.
21. The method for positioning two layout patterns of claim 11,
wherein positioning said second overlay mark comprises: detecting
said first overlay mark and said second overlay mark together
optically to obtain an optical data; and resolving said optical
data to respectively position said first overlay mark and said
second overlay mark.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to an overlay mark
set and a method for positioning two different layout patterns. In
particular, the present invention is directed to an overlay mark
set in which a first overlay mark is indirect contact with a second
overlay mark when the overlay mark set is in use for positioning
two different layout patterns on a same surface of a substrate. The
present invention is also directed to a method for positioning two
different layout patterns on a same surface of a substrate by using
an overlay mark set in which a first overlay mark is able to be
indirect contact with a second overlay mark when the overlay mark
set is in use.
[0003] 2. Description of the Prior Art
[0004] Semiconductor integrated circuits undergo a variety of
processing steps during their manufacture, such as masking, resist
coating, etching, and deposition. In many of these steps, material
is overlaid or removed from the existing layer at specific
locations in order to form the desired elements of the integrated
circuit. Proper overlay of the various process layers is therefore
critical. The shrinking dimensions of modern integrated circuits
require more and more stringent overlay accuracy during the pattern
transfer step. If the expected overlay tolerance is not met, the
adverse result is a device that is defective or has reliability
problems.
[0005] Registration is typically used to measure the accuracy of a
process layer overlay performed using an overlay mark. Registration
involves comparing the position of a subsequent layer to that of an
existing layer by overlaying a distinct pattern on a matching
pattern previously formed on the existing layer. The deviation in
position of the overlay from the original provides a measure of
accuracy of the overlay. Currently available registration
structures include box-in-box visual verniers to determine the
amount of overlay offset. A conventional overlay mark set of the
box-in-box type usually includes two different overlay marks. The
inner and outer overlay marks for, respectively, the previous layer
and the current layer do not contact each other.
[0006] When the conventional overlay mark set is used, a first
overlay mark and a second overlay mark in the conventional overlay
mark set are respectively disposed in two different layers on the
substrate. The bottom overlay mark (the first overlay mark for
instance) is formed along with a previous pattern beneath the
second overlay mark. The top overlay mark (the second overlay mark
for example) is formed along with a current pattern on top of the
first overlay mark and without directly contacting the first
overlay mark. The two overlay marks may vertically form a
box-in-box pattern to indicate the misalignment between the
previous pattern and the current pattern. The conventional overlay
mark set is not suitable for positioning two different layout
patterns on a same surface of a substrate accordingly.
[0007] Therefore, when it comes to positioning two different layout
patterns on a same surface of a substrate, a novel overlay mark set
as well as novel method are still needed.
SUMMARY OF THE INVENTION
[0008] Given the above, the present invention in a first aspect
proposes a novel overlay mark set for positioning two different
layout patterns on a same surface of a substrate. In particular,
the two overlay marks may be in direct contact with each other when
in use. The present invention also proposes a method for
positioning two different layout patterns on a same surface of a
substrate by using an overlay mark set in which a first overlay
mark and a second overlay mark may be formed on the same surface of
the substrate.
[0009] The overlay mark set of the present invention includes a
substrate, a first overlay mark and a second overlay mark. The
first overlay mark is disposed on the substrate for representing a
first layout pattern. The second overlay mark is also disposed on
the substrate for representing a second layout pattern. In
particular, the first overlay mark is in direct contact with the
second overlay mark.
[0010] In one embodiment of the present invention, the first layout
pattern is disposed on the substrate and the second layout pattern
is disposed on the same substrate.
[0011] In another embodiment of the present invention, the first
layout pattern includes a plurality of first segments and the
second layout pattern includes a plurality of second segments. The
first segments and the second segments are disposed in an alternate
fashion.
[0012] In another embodiment of the present invention, the first
overlay mark represents a previous layout pattern.
[0013] In another embodiment of the present invention, the second
overlay mark represents a current layout pattern.
[0014] In another embodiment of the present invention, the second
overlay mark is higher than the first overlay mark.
[0015] In another embodiment of the present invention, the first
overlay mark is a polygon.
[0016] In another embodiment of the present invention, the first
overlay mark is oval.
[0017] In another embodiment of the present invention, the second
overlay mark is a polygon.
[0018] In another embodiment of the present invention, the second
overlay mark is oval.
[0019] The present invention in a second aspect proposes a novel
method for positioning two different layout patterns on the same
surface. First, a substrate is provided. Second, a first layout
pattern and a first overlay mark are formed on the substrate. The
first overlay mark is processed, and a second layout pattern and a
second overlay mark are formed on the substrate so that the second
overlay mark is indirect contact with the first overlay mark. Then,
the second layout pattern is positioned and compared with the first
overlay mark.
[0020] In one embodiment of the present invention, the formation of
the first layout pattern and the first overlay mark on the
substrate includes the following steps. First, a first material
layer is formed on the substrate. The first layout pattern is
transferred into the first material layer by exposure and
development.
[0021] In another embodiment of the present invention, the
processing of the first overlay mark includes hard-baking the first
overlay mark.
[0022] In another embodiment of the present invention, the
formation of the second layout pattern and the second overlay mark
on the substrate includes the following steps. First, a second
material layer is formed on the substrate so that the second
material layer covers the first layout pattern. Then, the second
layout pattern is transferred into the second material layer by
exposure and development.
[0023] In another embodiment of the present invention, the first
layout pattern and the second layout pattern are disposed in
alternate order.
[0024] In another embodiment of the present invention, the method
for positioning two layout patterns further includes the step of
positioning the first overlay mark.
[0025] In another embodiment of the present invention, the step of
positioning the first overlay mark includes recording the position
of the first overlay mark digitally.
[0026] In another embodiment of the present invention, the step of
positioning the first overlay mark includes taking an image of the
first overlay mark.
[0027] In another embodiment of the present invention, the step of
positioning the second overlay mark may include the following
stages. First, the position of the second overlay mark and the
first overlay mark is recorded digitally together. Then, the
position of the second overlay mark and the first overlay mark is
compared with the position of the first overlay mark alone.
[0028] In another embodiment of the present invention, the step of
positioning the second overlay mark may include the following
stages. First, an image of the first overlay mark and the second
layout pattern together is taken. Then, the image of the first
overlay mark and the second overlay mark is compared with the image
of the first overlay mark alone.
[0029] In another embodiment of the present invention, the step of
positioning the second overlay mark may include the following
stages. First, the first overlay mark and the second overlay mark
together are detected optically to obtain optical data. Then, the
optical data is resolved to respectively position the first overlay
mark and the second overlay mark.
[0030] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIGS. 1-2 illustrate the overlay mark set of the present
invention.
[0032] FIGS. 3-11 illustrate the methods for positioning two
different layout patterns according to the present invention.
DETAILED DESCRIPTION
[0033] The present invention in a first aspect provides a novel
overlay mark set. The overlay mark set is suitable for positioning
two different layout patterns on a same surface of a substrate,
particularly when using a pitch-doubling technique. FIGS. 1-2
illustrate the overlay mark set of the present invention. Please
refer to FIG. 1. The overlay mark set 100 of the present invention
includes a substrate 101, a first overlay mark 110 and a second
overlay mark 120. The substrate 101 may be a semiconductor
substrate, such as Si, or a multi-layer substrate. The multi-layer
substrate may include previously formed elements, such as CMOS,
contact plugs or interconnection.
[0034] The first overlay mark 110 is disposed on a surface 102 of
the substrate 101. The first overlay mark 110 is formed along with
a first layout pattern 130 on the surface 102 of the substrate 101
for representing the relative position of the first layout pattern
130. Accordingly, the first overlay mark 110 and the first layout
pattern 130 may be of the same material.
[0035] The second overlay mark 120 is also disposed on the same
surface 102 of the substrate 101. Like the first overlay mark 110,
the second overlay mark 120 is formed along with a second layout
pattern 140 on the surface 102 of the substrate 101 for
representing the relative position of the second layout pattern
140. Similarly, the second overlay mark 120 and the second layout
pattern 140 may be of the same material.
[0036] As shown in FIG. 1, one feature of the present invention is
that the first overlay mark 110 is in direct contact with the
second overlay mark 120. For example, the first overlay mark 110
may cover part of the second overlay mark 120 so the first overlay
mark 110 is higher than the second overlay mark 120, or otherwise
the second overlay mark 120 may cover part of the first overlay
mark 110 so the second overlay mark 120 is higher than the first
overlay mark 110, depending on which one is formed first. As shown
in FIG. 2, the first overlay mark 110 or the second overlay mark
120 may be of various shapes provided they are not round, such as
oval, polygonal or in the form of a cross.
[0037] In one embodiment of the present invention, the first
overlay mark 110 is formed along with a previously formed layout
pattern for representing the relative position of the previously
formed layout pattern on the substrate 101, and the second overlay
mark 120 is formed along with a currently formed layout pattern for
representing the relative position of the currently formed layout
pattern on the same substrate 101.
[0038] In a pitch-doubling method, a later formed layout pattern is
formed in the neighborhood of a previously formed layout pattern
and the later formed layout pattern must be aligned with the
previously formed layout pattern to an extremely high precision. In
such a scenario, the overlay mark set 100 of the present invention
may exhibit a good utility.
[0039] In another embodiment of the present invention, the first
layout pattern 130 and the second layout pattern 140 may be
arranged in an alternate fashion. For example, as shown in FIG. 1,
the first layout pattern 130 may include a plurality of first
segments 131 and the second layout pattern 140 may include a
plurality of second segments 141 so that the first segments 131 and
second segments 141 are disposed in an alternate fashion. This
arrangement is particularly common in the pitch-doubling
method.
[0040] The present invention in a second aspect provides a method
for positioning two different layout patterns on the same
substrate, particularly when using a pitch-doubling technique.
FIGS. 3-11 illustrate the methods for positioning two different
layout patterns of the present invention. Please refer to FIG. 3.
First, a substrate 101 is provided. The substrate 101 may be a
semiconductor material such as Si and used in a pitch-doubling
process. Second, a first layout pattern 130 and a first overlay
mark 110 are together formed on the substrate 101. The first
overlay mark 110 usually serves as the reference of the first
layout pattern 130. The formation of the first layout pattern 130
and the first overlay mark 110 on the substrate 101 may be as
follows. First, a first material layer 135 is formed on the
substrate 101. The first material layer 135 may be a photoresist.
Then, the first layout pattern 130 is transferred into the first
material layer 135 by lithographic exposure and development. After
the development, the first material layer 135 becomes the first
layout pattern 130 with multiple first segments 131 of a specific
pitch: for example, twice the needed pitch.
[0041] Optionally, as shown in FIG. 4, the first overlay mark 110
is processed. For example, the processing of the first overlay mark
110 acts to denature the first material layer 135 of the first
overlay mark 110 so that the first material layer 135 and the first
overlay mark 110 are no longer the same. In one embodiment of the
present invention, the first overlay mark 110 may be processed by
hard-baking
[0042] In another embodiment of the present invention, the method
for positioning two layout patterns of the present invention may
further include the optional step(s) of positioning the first
overlay mark 110 in advance.
[0043] In one example, as shown in FIG. 5, the step of positioning
the first overlay mark 110 may include recording the position of
the first overlay mark 110 digitally. For example, the position of
the first overlay mark 110 is recorded digitally by a computer 160
in accordance with its coordination.
[0044] In another example, as shown in FIG. 6, the step of
positioning the first overlay mark 110 includes taking an image of
the first overlay mark 110 by an apparatus 161. For example, after
the development or the hard-baking, a picture is taken by the
apparatus 161 to record the shape and the location of the first
overlay mark 110.
[0045] Next, a second layout pattern 140 and a second overlay mark
120 are formed together on the substrate 101 so that the second
overlay mark 120 is in direct contact with the first overlay mark
110. The formation of the second layout pattern 140 and the second
overlay mark 120 on the substrate 101 may be as follows. First, as
shown in FIG. 7, a second material layer 145 is formed on the
substrate 101 so that the second material layer 145 covers the
first layout pattern 130. The first material layer 135 may also be
a photoresist. Then, as shown in FIG. 8, the second layout pattern
140 is transferred into the second material layer 145 by
lithographic exposure and development. After the development, the
second material layer 145 becomes the second layout pattern 140
with multiple second segments 141 and the second overlay mark 120.
The second overlay mark 120 is in direct contact with the first
overlay mark 110. For example, the second overlay mark 120 may
cover part of the first overlay mark 110. Similarly, the second
layout pattern 140 may have multiple second segments 141 of a
specific pitch so that the pitch of two adjacent first segments 131
and second segments 141 is the same according to requirements; the
second layout pattern 140 does not need denaturing, however.
[0046] In one embodiment of the present invention, as shown in FIG.
8, the first layout pattern 130 and the second layout pattern 140
are disposed in alternate order. For example, the first segments
131 and second segments 141 are disposed in an alternate
fashion.
[0047] The first overlay mark 110 and the second overlay mark 120
may not have the same height. For example, as shown in FIG. 8, the
second overlay mark 120 may cover part of the first overlay mark
110 so the second overlay mark 120 is higher than the first overlay
mark 110. Please refer to FIG. 2, which shows the first overlay
mark 110 and the second overlay mark 120 may be of various shapes
provided they are not round, such as oval, polygonal or in the
shape of a cross.
[0048] As shown in FIG. 9, the second overlay mark 120 is
positioned and compared with the first overlay mark 110. There are
various ways of carrying out the positioning and comparison. In a
first example of the present invention, the positioning of the
second overlay mark 120 may include the following steps.
[0049] The position of the second overlay mark 120 and the first
overlay mark 110 is recorded digitally together by a computer 160
so the digital information represents both the second overlay mark
120 and the first overlay mark 110. Then, the position of the
second overlay mark 120 and the first overlay mark 110 (namely, the
digital information of the second overlay mark 120 and the first
overlay mark 110) is compared with the digital information of the
first overlay mark 110 recorded previously by the computer 160. Via
subtraction of the first overlay mark 110, the overlay of the
second layout pattern 140 with respect to the first layout pattern
130 is revealed. Generally, the smaller the amount of the second
layout pattern 140 that remains, the better the overlay.
[0050] In a second example of the present invention, the
positioning of the second overlay mark 120 may include the
following steps. First, as shown in FIG. 6, an image of the first
overlay mark 110 is taken alone by an apparatus 161. Then, as shown
in FIG. 10, the image of the first overlay mark 110 and the second
overlay mark 120 is taken again by the apparatus 161 and compared
with the image of the first overlay mark 110 alone. Via this
comparison, the overlay of the second layout pattern 140 with
respect to the first layout pattern 130 is revealed. Generally, the
more the second layout pattern 140 overlaps with the first overlay
mark 110, the better the overlay.
[0051] In a third example of the present invention, the positioning
of the second overlay mark 120 may include the following steps.
First, as shown in FIG. 11, the first overlay mark 110 and the
second overlay mark 120 together are detected optically by an
optical device 162 to obtain an optical data when the first overlay
mark 110 is processed. When the first overlay mark 110 is
previously processed and the second overlay mark 120 is not, the
first overlay mark 110 and the second overlay mark 120 should be
optically distinct. Then, the optical data is resolved to
respectively position the first overlay mark 110 and the second
overlay mark 120 and to determine the overlay of the second overlay
mark 120 with respect to the first overlay mark 110.
[0052] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention.
* * * * *